During the course of particle therapy, a patient is generally irradiated with high-energy particles. Particle therapy utilizes an inverse dosage distribution, which has a low dosage of high energy particles at the edges of the particle beam and a high dosage of high energy particles in the area of the maximum penetration range. The maximum penetration range is, for example, the desired area of interaction with the irradiated tissue. Generally, the maximum penetration range is called the Bragg peak, which is a function of the energy of the particles in the particle beam and is set with high accuracy in the direction of the radiation by varying the particle energy distribution.
The width of the Bragg peak is determined by the clarity of the incoming particles. As described in “Design and Construction of a Ripple Filter for a Smoothed Depth Dose Distribution in Conformal Particle Therapy”, Phys. Med. Biol. 44 (1999), U. Weber and G. Kraft described on pp. 2765 to 2755, a ripple filter with a raster scanning device has been used in particle therapy to widen the Bragg peak. Other passive devices, which modulate the Bragg peak, have also been used in particle therapy. Devices such as propeller and edge filters, for example, utilize scattering technology and are used to widen the Bragg peak. Propeller and edge filters, for example, either rapidly rotate or rapidly move back and forth in the particle beam to spatially overlap the Bragg maximum. Scattering technology matches the orientation of the Bragg peak with the desired depth of the radiation.
Conventional passive beam-shaping devices, for example, ripple filters, are made of rigid materials, such as PMMA or aluminum. Such materials are formed with high precision and are susceptible to damage when bent or deformed (see the special design of the groove structure in U. Weber and G. Kraft).
It is advantageous if passive beam-shaping elements are guided into and out of an operation position; however, this movement increases the stress on the beam-shaping elements. Thus, the possibility of damage to the beam-shaping element is increased. The installation and removal of the beam-shaping element requires a substantial amount of special area because of the rigid structure of the device. Accordingly, there is a need for a device for expanding, monitoring, or adapting a particle energy distribution of a therapeutic particle radiation distribution that is easily operable, durable, and space efficient.